This invention relates generally to vessels that employ sub-hulls to reduce drag and improve stability. Vessels of this kind are disclosed in U.S. Pat. Nos. 4,452,166, 4,345,533, 3,960,100, 3,897,744, 3,842,772, 3,623,444, 3,541,987 and 3,447,502. In general, most of these prior art patents are concerned with improving the stability and speed of a vessel by the use of submerged cylindrical hulls either alone or in conjunction with a platform.